One of the biggest problems in installing fiber-optics systems, wherein data is communicated in fiber-optic cables, is the necessity for providing one cable for a number of homes or businesses, tapping into the one cable for each location, in a manner similar to the current style of telephone cable installation. Unfortunately, fiber-optic systems don""t lend themselves easily to such an approach, and typically what is required is to have either one dedicated cable run to each home or business, or to make a complete splicing of a common cable for each home. Both of these options are prohibitively expensive, and in some cases, inserting full taps reduces reliability dramatically.
What is needed is a method and a system that allows creation of junctions at different positions along a fiber-optic cable inexpensively and quickly, and without compromising reliability, to allow inexpensive upgrading to fiber-optic cabling in homes, businesses, and so on.
In a preferred embodiment of the present invention an apparatus for interfacing optical signals to an optical fiber is provided, comprising a layered interface element comprising a first electrically conductive layer defining a first surface, a photoactive material layer in intimate contact with the first layer on a second surface opposite the first surface, a second electrically conductive layer in intimate contact with the photoactive material layer, confining the photoactive material layer between the first and second electrically conductive layers, and a third surface angularly disposed to the first surface and intersecting the photoactive material layer; and a pressure element having a contact surface translatable toward the first surface of the interface element, to urge an optical fiber positioned across the interface element into the first surface, and by local deformation of the optical fiber also into the third surface, creating thereby an intimate contact region between an edge of the photoactive layer intersecting the third surface and the optical fiber.
In some cases the photoactive material is a photosensitive material, and light intercepted by the photosensitive layer is converted to a voltage between the first and second conductive layers. Also in preferred embodiments there are electrodes implemented on the two electrically conductive layers, the electrodes connected to electrical circuitry for forming an electrical signal in response to the light intercepted by the photosensitive material. In still other cases there are electrodes implemented on the two conductive layers to apply voltage signals to the photoactive material layer, and the photoactive material is a material that emits light in response to the electrical signals applied, and the light emitted is edge-emitted into the optical fiber at the intimate contact region.
In some embodiments of the invention the pressure element has a resilient covering on the contact surface to avoid damage to the optical fiber placed under pressure. There may also be a plurality of separate interface elements extending from a common layered structure, the separate interface elements spaced apart by a distance related to the wave-length of light to be transmitted in an optical fiber to be interfaced to the apparatus. Still further, there is, in some embodiments, an optically-occluding covering upon each of the plurality of interface elements on a side opposite the side of the third surface. The interface element and the pressure element are preferably joined by a translation mechanism allowing translation of the pressure element toward the interface element, which may be a hinge connected to each of the interface element and the pressure element.
In another aspect of the invention a method for non-invasive interfacing of signals to an optical fiber is provided, comprising the steps of (a) forming a layered interface element comprising a first electrically conductive layer defining a first surface, a photoactive material layer in intimate contact with the first layer on a second surface opposite the first surface, a second electrically conductive layer in intimate contact with the photoactive material layer, confining the photoactive material layer between the first and second electrically conductive layers, and a third surface angularly disposed to the first surface and intersecting the photoactive material layer; and (b) urging an optical fiber positioned across the interface element into the first surface, and by local deformation of the fiber into the third surface, by a pressure element having a contact surface translatable toward the first surface of the interface element, creating thereby an intimate contact region between an edge of the photoactive layer intersecting the third surface and the optical fiber.
In some embodiments of the method the photoactive material is a photosensitive material, and light intercepted by the photosensitive layer is converted to a voltage between the first and second conductive layers. In this embodiment electrodes are implemented on the two electrically conductive layers, the electrodes connected to electrical circuitry for forming an electrical signal in response to the light intercepted by the photosensitive material.
In other embodiments the electrodes are implemented on the two conductive layers to apply voltage signals to the photoactive material layer, the photoactive material is a material that emits light in response to the electrical signals applied, and the light emitted is edge-emitted into the optical fiber at the intimate contact region.
In some cases the pressure element has a resilient covering on the contact surface to avoid damage to the optical fiber placed under pressure. There may also be a plurality of separate interface elements extending from a common layered structure, the separate interface elements spaced apart by a distance related to the wave-length of light to be transmitted in an optical fiber to be interfaced to the apparatus. In some cases as well there is an optically occluding covering upon each of the plurality of interface elements on a side opposite the side of the third surface.
In preferred embodiments the interface element and the pressure element are joined by a translation mechanism allowing translation of the pressure element toward the interface element, and the interface element may be a hinge connected to each of the interface element and the pressure element.
In another aspect of the invention an optical fiber constructed to interface to a non-invasive signal transformation apparatus is provided, the fiber comprising a substantially constant diameter along a longitudinal axis of the fiber; and indentions implemented at repeated distances along the fiber to interface the fiber to one or more layered interface elements, the interface elements each comprising a first electrically conductive layer defining a first surface, a photoactive material layer in intimate contact with the first layer on a second surface opposite the first surface, a second electrically conductive layer in intimate contact with the photoactive material layer, confining the photoactive material layer between the first and second electrically conductive layers, and a third surface angularly disposed to the first surface and intersecting the photoactive material layer. The indentions are shaped to engage the interface elements in a manner that brings an edge of the photoactive material layer into intimate contact with a region of the fiber at an angle other than at a right angle to the longitudinal axis of the fiber. In some cases individual ones of said indentions are formed on opposite sides of a diameter of the fiber.
In still another aspect of the invention a method for interfacing an optical fiber to a non-invasive layered interface element comprising a first electrically conductive layer defining a first surface, a photoactive material layer in intimate contact with the first layer on a second surface opposite the first surface, a second electrically conductive layer in intimate contact with the photoactive material layer, confining the photoactive material layer between the first and second electrically conductive layers, and a third surface angularly disposed to the first surface and intersecting the photoactive material layer is provided, the method comprising the steps of (a) forming an indention in the fiber substantially at a right angle to a longitudinal axis of the fiber, the indention shaped to contact the interface element in a first indention region with the first surface substantially parallel to the longitudinal axis of the fiber, and with the third surface and the edge of the photoactive material layer in contact with a second region of the indention, the edge of the photoactive region then facing into the fiber at an angle other than at a right angle with the longitudinal axis of the fiber; and (b) engaging the interface element with the indention. In some embodiments of this method, in step (a), indentions are formed at repeated intervals along a length of the fiber.
In still another aspect of the present invention an optical cable for N fibers to enhance selectively coupling to individual fiber pairs from the cable is provided, comprising a first core conducting N-2 of the fibers, a second core parallel to the first core, the second core at any point conducting 2 of the N fibers, the second core physically distinguishable from the first core, and crossover regions at regular intervals along the cable having openings between the cores wherein fiber pairs may switch between the first core to the second core. The cable in this aspect is characterized in that at each crossover region proceeding in one direction, a pair of fibers in the second core crosses over into the first core, and a different pair of fibers crosses over from the first core to the second core.
In a preferred embodiment, at each crossover region, a different pair of fibers enters the second core, until all fibers have been in the second core, and then the sequence repeats. In this embodiment the cable may be annotated in each region between crossover points, identifying the cable pair in the region annotated. In another embodiment each fiber is associated with an electrical conductor in a manner that all fiber pairs may be identified from without the cable.
In still another embodiment a method for facilitating selective coupling to individual fiber pairs in an optical cable carrying N fibers in a plurality of fiber pairs is provided, comprising the steps of (a) forming the cable with a first core conducting N-2 of the fibers; (b) forming a second core parallel to the first core, the second core at any point conducting 2 of the N fibers, the second core physically distinguishable from the first core; (c) providing crossover regions at regular intervals along the cable, the crossover regions having an opening between the cores wherein fiber pairs may cross over between the first core and the second core; and (d) crossing a pair of fibers from the second core to the first core, and a different pair of fibers from the first core to the second core, at each crossover point. In some cases, at each crossover region a different pair of fibers enters the second core, until all fibers have been in the second core, and then the sequence repeats. In other cases the cable is annotated in each region between crossover points, identifying the fiber pair in the region annotated.
In various embodiments of the invention, taught in enabling embodiments below, for the first time a way is provided for interfacing to optical cables without a need to cut and splice fibers of the cables in most cases.